What Happens After Hell Cools?

"For behold, the day comes, burning like an oven, when all the arrogant and all evildoers will be stubble; the day that comes shall burn them up, says The Lord of hosts, so that it will leave them neither root nor branch. But for you who fear My Name the sun of righteousness shall rise, with healing in its wings. You shall go forth leaping like calves from the stall. And you shall tread down the wicked, for they will be ashes under the soles of your feet, on the day when I act, says The Lord of hosts. Remember the Law of My servant Moses, the statutes and ordinances [see The Ten Commandments and
The Ten Commandments Now?] that I commanded him at Horeb for all Israel [see Physical and Spiritual Israel and Daughter of Zion]. Behold, I will send you Elijah the prophet [see The Elijah To Come] before the great and terrible day of The Lord comes" (Malachi 4:1-5 RSV)

Another Flood Is Coming

After The Flood that God sent upon the earth to destroy all that was evil, God promised that never again would there be another flood, of water, that will cover all of the earth. But another flood is coming, not of water, but of fire. It will be a planet-wide ocean of fire that will purify, but not destroy, the entire earth, once and for all, after all Judgment (see When Will You Be Judged?) has been completed. The only survivors will be those who have been found worthy, by repentance and obedience to God, and made spirit. Here's what The Bible plainly has to say about it:

"First of all you must understand this, that scoffers will come in the last days with scoffing, following their own passions and saying, "Where is the promise of His coming? For ever since the fathers fell asleep, all things have continued as they were from the beginning of creation." They deliberately ignore this fact, that by the Word of God heavens existed long ago, and an earth formed out of water and by means of water [see Hydrogen], through which the world that then existed was deluged with water and perished. But by the same word the heavens and earth that now exist have been stored up for fire [again, see Hydrogen], being kept until the day of Judgment and destruction of ungodly men." (2 Peter 3:3-7 RSV)

"And I saw the dead, great and small, standing before the Throne, and books were opened. Also another book was opened, which is the book of life. And the dead were judged by what was written in the books, by what they had done. And the sea gave up the dead in it, Death and Hades gave up the dead in them, and all were judged by what they had done. Then Death and Hades were thrown into the lake of fire. This is the second death, the lake of fire; and if any one's name was not found written in the book of life, he was thrown into the lake of fire." (Revelation 20:12-15 RSV)

What Happens After "Hell" Cools?

"Then I saw a new heaven and a new earth; for the first heaven and the first earth had passed away, and the sea was no more. And I saw the holy city, new Jerusalem, coming down out of heaven from God [see The City To Come], prepared as a bride adorned for her husband; and I heard a loud voice from the Throne [see The Throne Of God, From Heaven To Earth] saying, "Behold, the dwelling of God is with men. He will dwell with them, and they shall be His people, and God Himself will be with them; He will wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning nor crying nor pain any more, for the former things have passed away." (Revelation 21:1-4 RSV)
(Note: "His people" in the verse above refers not to mortal, physical people but to those for whom "death shall be no more" i.e. they will at that time have been transformed to spirit)

Fact Finder: How did the term "hell" originate? What does the Bible actually say about "hell"?
See Where Is Hell?